Percutaneous spinal implants and methods

ABSTRACT

Spinal implants and methods for the placement thereof are disclosed herein. In one variation, the implant includes a support member, a proximal retention member, and a distal retention member. The support member is configured to be disposed between adjacent spinous processes. The proximal retention member has a first configuration in which the proximal retention member is substantially disposed within a proximal portion of the support member, and a second configuration in which a portion of the proximal retention member is disposed outside of the support member. The distal retention member has a first configuration in which the distal retention member is substantially disposed within a distal portion of the support member, and a second configuration in which a portion of the distal retention member is disposed outside of the support member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent application Ser. No. 11/252,879, entitled “Percutaneous Spinal Implants and Methods,” filed Oct. 19, 2005; and U.S. patent application Ser. No. 11/252,880, entitled “Percutaneous Spinal Implants and Methods,” filed Oct. 19, 2005, each of which is a continuation-in-part of U.S. patent application Ser. No. 11/059,526, entitled “Apparatus and Method for Treatment of Spinal Conditions,” filed Feb. 17, 2005, each of which are incorporated herein by reference in its entirety. This application also claims the benefit of U.S. Provisional Application Ser. No. 60/695,836 entitled “Percutaneous Spinal Implants and Methods,” filed Jul. 1, 2005, which is incorporated herein by reference in its entirety.

This application is related to U.S. patent application Attorney Docket Nos. KYPH-001/04US, KYPH-001/06US, KYPH-001/07US, and KYPH-001/08US each entitled “Percutaneous Spinal Implants and Methods,” and filed on even date herewith, each of which is incorporated herein by reference in its entirety.

BACKGROUND

The invention relates generally to percutaneous spinal implants, and more particularly, to percutaneous spinal implants for implantation, for example, between adjacent spinous processes.

Spinal stenosis is a back condition that impacts many individuals. Spinal stenosis is a progressive narrowing of the spinal canal that causes compression of the spinal cord. Each vertebra in the spinal column has an opening that extends through it. The openings are aligned vertically to form the spinal canal. The spinal cord runs through the spinal canal. As the spinal canal narrows, the spinal cord and nerve roots extending from the spinal cord and between adjacent vertebrae are compressed and can become inflamed. Spinal stenosis can cause pain, weakness, numbness, burning sensations, tingling, and in particularly severe cases, may cause loss of bladder or bowel function, or paralysis. The legs, calves and buttocks are most commonly affected by spinal stenosis, however, the shoulders and arms may also be affected.

Mild cases of spinal stenosis may be treated with rest or restricted activity, non-steroidal anti-inflammatory drugs (e.g., aspirin), corticosteroid injections (epidural steroids), and/or physical therapy. Some patients find that bending forward, sitting or lying down may help relieve the pain. In such instances, the pain relief may result from the action of bending forward, which may create more vertebral space in some instances, thereby temporarily relieving nerve compression. Because spinal stenosis is a progressive disease, surgery (i.e., decompressive laminectomy) may eventually be required to address the source of pressure causing the pain. Such known surgical procedures can involve removing bone and other tissues that have impinged upon the spinal canal and/or put pressure on the spinal cord. In some procedures, two adjacent vertebrae may also be fused to prevent an area of instability, improper alignment or slippage, such as that caused by spondylolisthesis. Surgical decompression can relieve pressure on the spinal cord or spinal nerve by widening the spinal canal to create more space. This procedure requires that the patient be given a general anesthesia as an incision is made in the patient to access the spine to remove the areas that are contributing to the pressure. Drawbacks of this procedure include the potential for blood loss, an increased chance of significant complications, and extended hospital stays.

Minimally-invasive procedures have been developed to provide access to the space between adjacent spinous processes such that major surgery of the type described above is not required. Such known procedures, however, may not be suitable in conditions where the spinous processes are severely compressed. Moreover, such known procedures may not allow various surgical implants to be repositioned or removed from the patient without requiring large or multiple incisions.

Thus, a need exists for improvements in the treatment of spinal conditions such as spinal stenosis.

SUMMARY

Apparatuses and methods for performing minimally-invasive medical procedures are described herein. In one embodiment, for example, an apparatus includes a support member, a proximal retention member, and a distal retention member. The support member is configured to be disposed between adjacent spinous processes. The proximal retention member has a first configuration in which the proximal retention member is substantially disposed within a proximal portion of the support member, and a second configuration in which a portion of the proximal retention member is disposed outside of the support member. The distal retention member has a first configuration in which the distal retention member is substantially disposed within a distal portion of the support member, and a second configuration in which a portion of the distal retention member is disposed outside of the support member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic illustration of a posterior view of a medical device according to an embodiment of the invention in a first configuration disposed between two adjacent spinous processes.

FIG. 1B is a schematic illustration of a posterior view of a medical device according to an embodiment of the invention in a second configuration disposed between two adjacent spinous processes.

FIGS. 2A and 2B are perspective views of a medical device according to an embodiment of the invention in a first configuration and a second configuration, respectively.

FIG. 3 is a posterior view of the medical device illustrated in FIGS. 2A and 2B disposed between adjacent spinous processes in a second configuration.

FIG. 4 is a lateral view taken from a proximal perspective A-A of the medical device illustrated in FIG. 3 disposed between adjacent spinous processes in a second configuration.

FIG. 5 is a cross-sectional front view of the medical device illustrated in FIGS. 2A and 2B in a second configuration.

FIG. 6 is a cross-sectional plan view taken along section A-A of the medical device illustrated in FIGS. 2A and 2B in a second configuration.

FIG. 7 is a cross-sectional front view of a medical device according to an embodiment of the invention in a second configuration.

FIGS. 8A and 8B are cross-sectional plan views taken along section A-A of the medical device illustrated in FIG. 7 in a second configuration and a first configuration, respectively.

FIG. 9 is a cross-sectional front view of a medical device according to an embodiment of the invention in a second configuration.

FIGS. 10A through 10C are cross-sectional plan views taken along section A-A of the medical device illustrated in FIG. 9 in a second configuration, a first configuration, and a third configuration respectively.

FIGS. 11A and 11B are cross-sectional front views of a medical device according to an embodiment of the invention in a second configuration and a first configuration, respectively.

FIG. 12 is a cross-sectional front view of a medical device according to an embodiment of the invention in a second configuration.

FIG. 13 is a cross-sectional plan view taken along section A-A of the medical device illustrated in FIG. 12 in a second configuration.

FIGS. 14A and 14B are perspective views of a medical device according to an embodiment of the invention in a second configuration and a first configuration, respectively.

FIGS. 15A and 15B are lateral views of a medical device according to an embodiment of the invention in a first configuration and a second configuration, respectively.

FIGS. 16A and 16B are perspective views of the medical device illustrated in FIGS. 15A and 15B in a first configuration and a second configuration, respectively.

FIG. 17 is a cross-sectional plan view of the medical device illustrated in FIGS. 15A and 15B in a second configuration.

DETAILED DESCRIPTION

In one variation, the apparatus includes a support member, a proximal retention member, and a distal retention member. The support member is configured to be disposed between adjacent spinous processes. The proximal retention member has a first configuration in which the proximal retention member is substantially disposed within a proximal portion of the support member and a second configuration in which a portion of the proximal retention member is disposed outside of the support member. The distal retention member has a first configuration in which the distal retention member is substantially disposed within a distal portion of the support member and a second configuration in which a portion of the distal retention member is disposed outside of the support member.

In some embodiments, each of the proximal retention member and the distal retention member includes a first elongate member and a second elongate member. The second elongate member is configured to be slidably disposed within the first elongate member. The support member includes a side wall defining a multiple openings, each opening being configured to receive a portion of at least one of the first elongate member or the second elongate member therethrough.

In some embodiments, each of the proximal retention member and the distal retention member includes an elongate member having a longitudinal axis and a rotating member having a longitudinal axis normal to the longitudinal axis of the elongate member. A portion of the elongate member is flexible in a direction normal to its longitudinal axis. The rotating member is coupled to the elongate member and configured to rotate about its longitudinal axis, thereby moving the elongate member along its longitudinal axis.

In some embodiments, a method includes percutaneously inserting into a body a support member configured to be disposed between adjacent spinous processes. The support member defines an inner area and an opening substantially normal to the longitudinal axis that connects the inner area and an area outside the support member. The support member includes a retention member having a first configuration in which the retention member is substantially disposed within the inner area, and a second configuration in which a portion of the retention member is disposed through the opening to the area outside the support member. The support member is disposed to a location between the adjacent spinous processes when retention member is in the first configuration. The retention member is moved from the first configuration to the second configuration.

Although specific portions of the apparatus, such as one or more retention members, are configured to move between a first, a second configuration and/or a third configuration, for ease of reference, the entire apparatus may be referred to as being in a first configuration, a second configuration and/or a third configuration. However, one of ordinary skill in the art having he benefit of this disclosure would appreciate that the apparatus may be configured to include four or more configurations. Additionally, in some embodiments, the apparatus can be in many positions during the movement between the first, second and/or third configurations. For ease of reference, the apparatus is referred to as being in either a first configuration, a second configuration or a third configuration. Finally, in some embodiments, although an apparatus includes one or more retention members, the figures and accompanying description may show and describe only a single retention member. In such instances, it should be understood that the description of a single retention member applies to some or all other retention members that may be included in the embodiment.

As used in this specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, the term “a member” is intended to mean a single member or a combination of members, “a material” is intended to mean one or more materials, or a combination thereof. Furthermore, the words “proximal” and “distal” refer to direction closer to and away from, respectively, an operator (e.g., surgeon, physician, nurse, technician, etc.) who would insert the medical device into the patient, with the tip-end (i.e., distal end) of the device inserted inside a patient's body first. Thus, for example, the implant end first inserted inside the patient's body would be the distal end of the implant, while the implant end to last enter the patient's body would be the proximal end of the implant.

FIGS. 1A and 1B are schematic illustrations of a posterior view of a medical device 3000 according to an embodiment of the invention disposed between two adjacent spinous processes S in a first configuration and a second configuration, respectively. The medical device 3000 includes a support member 3002, a proximal retention member 3010 and a distal retention member 3012. The support member 3002 has a proximal portion 3004 and a distal portion 3006, and is configured to be disposed between the spinous processes S to prevent over-extension/compression of the spinous processes S. In some embodiments, the support member 3002 distracts the adjacent spinous processes S. In other embodiments, the support member 3002 does not distract the adjacent spinous processes S.

The proximal retention member 3010 has a first configuration in which it is substantially disposed within the proximal portion 3004 of the support member 3002, as illustrated in FIG. 1A. Similarly, the distal retention member 3012 has a first configuration in which it is substantially disposed within the distal portion 3006 of the support member 3002. When the proximal retention member 3010 and the distal retention member 3012 are each in their respective first configuration, the medical device 3000 can be inserted between the adjacent spinous processes S.

The proximal retention member 3010 can be moved from the first configuration to a second configuration in which a portion of it is disposed outside of the support member 3002, as illustrated in FIG. 1B. Similarly, the distal retention member 3012 can be moved from the first configuration to a second configuration. When each is in their respective second configuration, the proximal retention member 3010 and the distal retention member 3012 limit lateral movement of the support member 3002 with respect to the spinous processes S by contacting the spinous processes S (i.e., either directly or through surrounding tissue). For purposes of clarity, the tissue surrounding the spinous processes S is not illustrated.

In use, the adjacent spinous processes S can be distracted prior to inserting the medical device 3000 into the patient. Distraction of spinous processes is disclosed, for example, in U.S. application Ser. No. 11/059,526, incorporated herein by reference in its entirety. When the spinous processes S are distracted, a trocar (not shown in FIGS. 1A or 1B) can be used to define an access passageway (not shown in FIGS. 1A and 1B) for the medical device 3000. In some embodiments, the trocar can be used to define the passage as well as to distract the spinous processes S.

Once an access passageway is defined, the medical device 3000 is inserted percutaneously and advanced, distal portion 3006 first, between the spinous processes S. The medical device 3000 can be inserted from the side of the spinous processes S (i.e., a posterior-lateral approach). The use of a curved shaft assists in the use of a lateral approach to the spinous processes S. Once the medical device 3000 is in place between the spinous processes S, the proximal retention member 3010 and the distal retention member 3012 are moved to their second configurations, either serially or simultaneously. In this manner, lateral movement of the support member 3002 with respect to the spinous processes S is limited.

When it is desirable to change the position of the medical device 3000, the proximal retention member 3010 and the distal retention member 3012 are moved back to their first configurations, thereby allowing the support member 3002 to be moved laterally. Once the support member 3002 is repositioned, the medical device 3000 can be returned to the second configuration. Similarly, when it is desirable to remove the medical device 3000, proximal retention member 3010 and the distal retention member 3012 are moved to their first configurations, thereby allowing the support member 3002 to be removed.

In some embodiments, the medical device 3000 is inserted percutaneously (i.e., through an opening in the skin) and in a minimally-invasive manner. For example, as discussed in detail herein, the overall sizes of portions of the medical device 3000 can be increased by moving the proximal retention member 3010 and the distal retention member 3012 to their respective second configurations after the medical device 3000 is inserted between the adjacent spinous processes S. When in the expanded second configuration, the sizes of portions of the medical device 3000 can be greater than the size of the opening. For example, the size of the opening/incision in the skin can be between 3 millimeters in length and 25 millimeters in length across the opening. In some embodiments, the size of the medical device 3000 in the expanded second configuration is between 3 and 25 millimeters across the opening.

FIGS. 2A, 2B, 3-6 illustrate a spinal implant 3100 according to an embodiment of the invention. FIGS. 2A and 2B are perspective views of the spinal implant 3100 in a first configuration and a second configuration, respectively. The spinal implant 3100 includes a support member 3102, a proximal retention member 3110 and a distal retention member 3112. The support member 3102 is positioned between adjacent spinous processes S, as illustrated in FIGS. 3 and 4. As shown in FIGS. 2A and 2B, the proximal retention member 3110 and the distal retention member 3112 are each repeatably positionable in a first configuration in which they are substantially disposed within the support member 3102 (FIG. 2A), and a second configuration in which a portion of each retention member 3110, 3112 is disposed outside of the support member 3102 (FIG. 2B). When the spinal implant 3100 is in the first configuration, it can be inserted between the adjacent spinous processes S, repositioned between the adjacent spinous processes and/or removed from the patient. When the spinal implant 3100 is in the second configuration, its lateral movement is limited, thereby allowing the desired position of the support member 3102 to be maintained.

In some embodiments, the support member 3102 distracts the adjacent spinous processes S. In other embodiments, the support member 3102 does not distract the adjacent spinous processes S. In yet other embodiments, the engagement of the spinous processes S by the support member 3102 is not continuous, but occurs upon spinal extension.

The support member 3102 can be made from any number of biocompatible materials, such as, for example, stainless steel, plastic, polyetheretherketone (PEEK), carbon fiber, ultra-high molecular weight (UHMW) polyethylene, and the like. The material of the support member 3102 can have a tensile strength similar to or higher than that of bone. In some embodiments, the support member 3102 is substantially rigid. In other embodiments, the support member 3102 or portions thereof is elastically deformable, thereby allowing it to conform to the shape of the spinous processes. In yet other embodiments, the support member 3102 includes a radiopaque material, such as bismuth, to facilitate tracking the position of the spinal implant 3100 during insertion and/or repositioning.

In the illustrated embodiment, the spinal implant 3100 includes a sensor 3124 coupled to the support member 3102. In some embodiments, the sensor 3124 is a strain gauge sensor that measures a force applied to the support member 3102. In some embodiments, the sensor 3124 can include multiple strain gauges to facilitate measuring multiple force quantities, such as a compressive force and/or a bending moment. In other embodiments, the sensor 3124 is a variable capacitance type pressure sensor configured to measure a force and/or a pressure applied to the support member 3102. In yet other embodiments, the sensor 3124 is a piezoelectric sensor that measures a force and/or a pressure applied to the support member 3102. In still other embodiments, the spinal implant 3100 can include multiple sensors located at various locations to provide a spatial profile of the force and/or pressure applied to the support member 3102. In this manner, a practitioner can detect changes in the patient's condition, such those that may result in a loosening of the spinal implant.

In some embodiments, the sensor 3124 can be remotely controlled by an external induction device. For example, an external radio frequency (RF) transmitter (not shown) can be used to supply power to and communicate with the sensor 3124. In other embodiments, an external acoustic signal transmitter (not shown) can be used to supply power to and communicate with the sensor 3124. One example of a implantable sensor configured to communicate to an external receiver using acoustic signals is given in U.S. Pat. No. 6,764,446, entitled “Implantable Pressure Sensors and Methods for Making and Using Them,” which is incorporated herein by reference in its entirety.

The support member 3102 includes a sidewall 3108 that defines an inner area 3120 and multiple openings 3114 that connect the inner area 3120 to an area outside of the support member 3102. When the spinal implant 3100 is in the first configuration, the proximal retention member 3110 and the distal retention member 3112 are substantially disposed within the inner area 3120 of the support member 3102, as shown in FIG. 2A. When the spinal implant 3100 is in the second configuration, a portion of each of the proximal retention member 3110 and the distal retention member 3112 extends through the openings 3114 to an area outside of the support member 3102. In the second configuration, the proximal retention member 3110 and the distal retention member 3112 engage the adjacent spinous processes, thereby limiting lateral movement of the spinal implant 3100.

The proximal retention member 3110 includes a first elongate member 3130 and a second elongate member 3132. Similarly, the distal retention member 3112 includes a first elongate member 3131 and a second elongate member 3133. As illustrated in FIG. 6, which shows is a cross-sectional plan view of the proximal portion 3104 of the support member 3102, the first elongate member 3130 is slidably disposed within a pocket 3134 defined by the second elongate member 3132. A biasing member 3136, such as a spring or an elastic member, is disposed within the pocket 3134 and is coupled to the first elongate member 3130 and the second elongate member 3132. In this manner, the retention members can be biased in the second configuration. In other embodiments, the biasing member 3136 can be configured to bias the retention members in the first configuration. In yet other embodiments, the retention members do not include a biasing member, but instead use other mechanisms to retain a desired configuration. Such mechanisms can include, for example, mating tabs and slots configured to lockably engage when the retention members are in a desired configuration.

In use, the spinal implant 3100 is positioned in the first configuration during insertion, removal or repositioning. As discussed above, the spinal implant 3100 is inserted percutaneously between adjacent spinous processes. The distal portion 3106 of the support member 3102 is inserted first and is moved past the spinous processes until the support member 3102 is positioned between the spinous processes. The support member 3102 can be sized to account for ligaments and tissue surrounding the spinous processes S. In some embodiments, the support member 3102 contacts the spinous processes between which it is positioned during a portion of the range of motion of the spinous processes S. In some embodiments, the support member 3102 of spinal implant 3100 is a fixed size and is not compressible or expandable. In yet other embodiments, the support member 3102 can compress to conform to the shape of the spinous processes S. Similarly, in some embodiments, the proximal retention member 3110 and the distal retention member 3112 are substantially rigid. In other embodiments, the retention members or portions thereof are elastically deformable, thereby allowing them to conform to the shape of the spinous processes.

In the illustrated embodiment, the spinal implant 3100 is held in the first configuration by an insertion tool (not shown) that overcomes the force exerted by the biasing member 3136, thereby disposing a portion of the first elongate member 3130 within the pocket 3134 of the second elongate member 3132. In this manner, the spinal implant 3100 can be repeatedly moved from the first configuration to the second configuration, thereby allowing it to be repositioned and/or removed percutaneously. As illustrated in FIG. 5, the first elongate member 3130 and the second elongate member 3132 each include notches 3138 configured to receive a portion of the insertion tool. When the insertion tool is released, the biasing member 3136 is free to extend, thereby displacing a portion of the first elongate member 3130 out of the pocket 3134 of the second elongate member 3132. In this manner, portions of both the first elongate member 3130 and the second elongate member 3132 are extended through the adjacent openings 3114 and to an area outside of the support member 3102. In some embodiments, the proximal retention member 3110 and the distal retention member 3112 are transitioned between their respective first and second configurations simultaneously. In other embodiments, the proximal retention member 3110 and the distal retention member 3112 are transitioned between their first and second configurations serially.

As illustrated, the first elongate member 3130 and the second elongate member 3132 each include one or more tabs 3140 that engage the side wall 3108 of the support member 3102 when in the second configuration, thereby ensuring that the first and second elongate members remain coupled to each other and that portions of the first and second elongate members remain suitably disposed within the support member 3102. In other embodiments, the first elongate member 3130 and the second elongate member 3132 are coupled to each other by other suitable mechanisms, such as mating tabs and slots configured to engage when the retention member reaches a predetermined limit of extension.

FIGS. 7, 8A and 8B are cross-sectional views of a spinal implant 3200 according to an embodiment of the invention. FIG. 7 illustrates a cross-sectional front view of the spinal implant 3200 in a second configuration, while FIGS. 8A and 8B illustrate a cross-sectional plan view of the spinal implant 3200 in the second configuration and a first configuration, respectively. The illustrated spinal implant 3200 includes a support member 3202, a retention member 3210 and a rotating member 3250. Although shown and described as including only a single retention member 3210, some embodiments can include one or more additional retention members having characteristics and functionality similar to those described for the retention member 3210.

As shown in FIGS. 8A and 8B, the retention member 3210 is repeatably positionable in a first configuration in which it is substantially disposed within the support member 3202, and a second configuration in which a portion the retention member 3210 is disposed outside of the support member 3102. When the spinal implant 3200 is in the first configuration, it can be inserted between adjacent spinous processes, repositioned between adjacent spinous processes and/or removed from the patient. When the spinal implant 3200 is in the second configuration, its lateral movement is limited, thereby allowing the desired position of the support member 3202 to be maintained.

The support member 3202 includes a sidewall 3208 that defines an inner area 3220 and multiple openings 3214 that connect the inner area 3220 to an area outside of the support member 3202. When the spinal implant 3200 is in the first configuration, the retention member 3210 is substantially disposed within the inner area 3220 of the support member 3202, as shown in FIG. 8B. When the spinal implant 3200 is in the second configuration, a portion of the proximal retention member 3210 extends through the openings 3214 to an area outside of the support member 3202. In the second configuration, the retention member 3210 is disposed adjacent the spinous processes, thereby limiting lateral movement of the spinal implant 3200.

The retention member 3210 includes an elongate member 3228 having two end portions 3244, a central portion 3242, and a longitudinal axis L1 (shown in FIG. 7). A portion of the elongate member 3228 is flexible such that it can be wound along the rotating member 3250, as described below. In some embodiments, the elongate member 3228 is monolithically formed such that it is flexible enough to be wound along the rotating member 3250 yet rigid enough to limit lateral movement of the support member 3202 when positioned in the second configuration. In other embodiments, the elongate member 3228 includes separate components that are coupled together to form the elongate member 3228. For example, the central portion 3242 of the elongate member 3228 can be a distinct component having a greater amount of flexibility, while the end portions 3244 can be distinct components having a greater amount of rigidity.

In the illustrated embodiment, elongate member 3228 has one or more tabs 3240 that engage the side wall 3208 of the support member 3202 when in the second configuration, thereby ensuring that the elongate member 3228 does not freely extend entirely outside of the support member 3202. In other embodiments, a portion of the elongate member 3228 is retained within the support member 3202 by other suitable mechanisms. For example, the width of the central portion 3242 of the elongate member 3228 can be greater than the width of the openings 3214, thereby ensuring that a portion of the elongate member 3228 will remain within the support member 3202.

The rotating member 3250 defines an outer surface 3252 and a slot 3254 through which the elongate member 3228 is disposed. The rotating member 3250 has a longitudinal axis L2 (shown in FIG. 7) about which it rotates. As illustrated in FIG. 8B, as the rotating member 3250 rotates, the elongate member 3228 is wound along the outer surface 3252 of the rotating member 3250. This causes the elongate member 3228 to move along its longitudinal axis L1, thereby causing the end portions 3244 of the elongate member 3228 to be retracted inwardly through the openings 3214. In this manner, the retention member 3210 can be repeatedly transitioned between the first configuration and the second configuration.

In some embodiments, the rotating member 3250 is rotated using an insertion tool (not shown) that includes a ratchet mechanism. The insertion tool can rotate the rotating member 3250 in a number of different ways, such as, for example, manually, pneumatically or electronically.

FIGS. 9 and 10A-10C are cross-sectional views of a spinal implant 3300 according to an embodiment of the invention. FIG. 9 illustrates a cross-sectional front view of the spinal implant 3300 in a second configuration, while FIGS. 10A-10C illustrate a cross-sectional plan view of the spinal implant 3300 in the second configuration, a first configuration, and a third configuration, respectively. The illustrated spinal implant 3300 includes a support member 3302 and a retention member 3310. Although shown and described as including only a single retention member 3310, some embodiments can include one or more additional retention members having characteristics and functionality similar to those described for the retention member 3310.

As shown in FIGS. 10A-10C, the retention member 3310 is repeatably positionable in a first configuration, a second configuration and a third configuration. A portion the retention member 3310 is disposed outside of the support member 3302 when positioned in the second configuration. The retention member 3310 is substantially disposed within the support member 3202 when positioned in each of the first and third configurations. As illustrated in FIGS. 10B and 10C, the orientation of the retention member 3310 differs between the first and third configurations. In this manner, the position of the spinal implant 3300 can be positioned appropriately depending on the direction in which it is being moved. For example, the spinal implant 3300 may be positioned in the first configuration to facilitate lateral movement of the support member 3302 in a distal direction, such as during insertion. Conversely, the spinal implant 3300 may be positioned in the third configuration to facilitate lateral movement of the support member 3302 in a proximal direction, such as during removal.

The support member 3302 includes a sidewall 3308 that defines an inner area 3320 and multiple openings 3314 that connect the inner area 3320 to an area outside of the support member 3302. When the spinal implant 3300 is in the second configuration, a portion of the proximal retention member 3310 extends through the openings 3314 to an area outside of the support member 3302.

The retention member 3310 includes a first elongate member 3330, a second elongate member 3332, and a hinge 3360 having a longitudinal axis L2 (shown in FIG. 9). Each of the first elongate member 3330 and the second elongate member 3332 has a distal end portion 3344 that extends through the openings 3314 when the spinal implant 3300 is in the second configuration and a proximal end portion 3346 that is pivotally coupled to the hinge 3360. In use, the hinge 3360 moves in a direction normal to its longitudinal axis L2, as indicated by the arrows in FIGS. 10B and 10C. The motion of the hinge is guided by a slot 3362 defined by the side wall 3308 of the support member 3302. The movement of the hinge 3360 allows the each of the first elongate member 3330 and the second elongate member 3332 to rotate about the longitudinal axis L2 of the hinge 3360, thereby positioning the distal end portion 3344 of each elongate member substantially within the inner area 3320 of the support member 3302.

In some embodiments, the slot 3362 includes detents or any other suitable mechanism (not shown) to maintain the hinge 3360 in the desired position. In other embodiments the hinge 3360 includes a biasing member (not shown) configured to bias the hinge 3360 in one of the first, second, or third configurations. In yet other embodiments, the elongate members include other suitable mechanisms to retain the retention member in a desired configuration. Such mechanisms can include, for example, mating tabs and slots configured to lockably engage when the elongate members are in a desired configuration.

In some embodiments, the first elongate member 3330 and the second elongate member 3332 are monolithically formed of a substantially rigid material. In other embodiments, the first elongate member 3330 and the second elongate member 3332 include separate components having different material properties. For example, the distal end portion 3344 can be formed from a material having a greater amount of flexibility, while the proximal end portion 3346 can be formed from a substantially rigid material. In this manner, movement of the spinal implant 3300 is not restricted when a portion of the of the distal end portion 3344 protrudes from the openings 3314 in either the first configuration or the third configuration.

FIGS. 11A and 11B are cross-sectional front views of a spinal implant 3400 according to an embodiment of the invention. The illustrated spinal implant 3400 includes a support member 3402, a retention member 3410 and a rotating member 3450. As shown in FIGS. 11A and 11B, the retention member 3410 is repeatably positionable in a first configuration in which it is substantially disposed within the support member 3402, and a second configuration in which a portion the retention member 3410 is disposed outside of the support member 3402. Although shown and described as including only a single retention member 3410, some embodiments include one or more additional retention members having characteristics and functionality similar to those described for the retention member 3410.

The support member 3402 includes a sidewall 3408 that defines an inner area 3420 and multiple openings 3414 that connect the inner area 3420 to an area outside of the support member 3402. When the spinal implant 3400 is in the second configuration, a portion of the proximal retention member 3410 extends through the openings 3414 to an area outside of the support member 3402.

The retention member 3410 includes a first elongate member 3430 and a second elongate member 3432, each having a distal end portion 3444 that extends through the openings 3414 when the spinal implant 3400 is in the second configuration, a proximal end portion 3446, and a longitudinal axis L1. As illustrated, the proximal end portions 3346 are coupled by two elastic members 3468, such as a spring or an elastic band. In some embodiments, the proximal end portions 3346 are coupled by a single elastic member. In other embodiments, the proximal end portions 3346 are indirectly coupled via the rotating member 3450. In such an arrangement, for example, a biasing member can be placed between the sidewall of the support member and each elongate member, thereby biasing each elongate member against the rotating member.

In the illustrated embodiment, the elongate members each include one or more tabs 3440 that engage the side wall 3408 of the support member 3402 when in the second configuration, thereby ensuring that the elongate members 3430, 3432 does not freely extend entirely outside of the support member 3402. In other embodiments, the elongate members do not include tabs, but are retained within the support member 3402 solely by the elastic members 3468. In yet other embodiments, the width of a portion of the elongate members can be greater than the width of the openings 3414, thereby ensuring that the elongate members will remain within the support member 3402.

The rotating member 3450 defines an outer surface 3452 having an eccentric shape and includes a longitudinal axis (not shown) about which it rotates. As illustrated in FIGS. 11A and 11B, as the rotating member 3450 rotates about its longitudinal axis, a portion of the proximal end portion 3346 of the first elongate member 3430 and the second elongate member 3432 engage the outer surface 3452 of the rotating member 3250. This causes the first elongate member 3430 and the second elongate member 3432 to move along their respective longitudinal axes L1, thereby causing the end portions 3444 of each elongate member to be extended outwardly through the openings 3414, as indicated by the arrows in FIG. 11A. In this manner, the retention member 3410 can be repeatedly transitioned between the first configuration and the second configuration.

In some embodiments, the rotating member 3450 is rotated using an insertion tool (not shown) that includes a ratchet mechanism. The insertion tool can rotate the rotating member 3450 in a number of different ways, such as, for example, manually, pneumatically or electronically.

FIGS. 12 and 13 illustrate a spinal implant 3500 according to an embodiment of the invention. FIG. 12 is a cross-sectional front view of the spinal implant 3500 in a second configuration. FIG. 13 is a cross-sectional plan view of the spinal implant 3500 taken along section A-A. The spinal implant 3500 includes a support member 3502 and a retention member 3510. Although only shown as being in a second or expanded configuration, it is understood from the previous descriptions that the retention member 3510 is repeatably positionable in a first configuration in which it is substantially disposed within the support member 3502, and the second configuration in which a portion the retention member 3510 is disposed outside of the support member 3502.

As illustrated, the retention member 3510 includes a first elongate member 3530 and a second elongate member 3532. The first elongate member 3530 is slidably disposed within a pocket 3534 defined by the second elongate member 3532. The first elongate member 3530 and the second elongate member 3532 each include one or more tabs 3540 that are coupled to the side wall 3508 of the support member 3502 by one or more biasing members 3536. In this manner, the retention member 3510 is biased in the first or retracted configuration. In other embodiments, the biasing members 3536 can be configured to bias the retention member 3510 in the second configuration. In yet other embodiments, the retention member 3510 is not retained by a biasing member 3536, but rather uses other suitable mechanisms to retain the desired configuration.

In use, the retention member 3510 is transitioned from the first configuration to the second configuration by supplying a pressurized fluid (not shown) to the pocket 3534 via valve 3570. The pressure exerted by the fluid on each of the first elongate member 3530 and the second elongate member 3532 overcomes the force exerted by the biasing members 3536, thereby causing a portion the first elongate member 3530 to extend outwardly from the pocket 3534 of the second elongate member 3132, thereby allowing a portion of each elongate member to extend through the adjacent openings 3514 and to an area outside of the support member 3502. Similarly, the retention member 3510 is transitioned from the second configuration to the first configuration by opening the valve 3570 and relieving the pressure within the pocket 3534. In this manner, the spinal implant 3500 can be repeatedly moved from the first configuration to the second configuration, thereby allowing it to be repositioned and/or removed percutaneously.

FIGS. 14A and 14B illustrate perspective views of a spinal implant 3600 according to an embodiment of the invention. The spinal implant 3600 includes a support member 3602, a proximal retention member 3610, a distal retention member 3612, and an elastic member 3668. The support member 3602 defines a longitudinal axis L1 and has a sidewall 3608 that defines an inner area 3620 and has an outer surface 3616. As illustrated in FIG. 14B, the outer surface 3616 defines an area A normal to the longitudinal axis L1. As shown, the proximal retention member 3610 and the distal retention member 3612 are each repeatably positionable in a first configuration in which they are substantially disposed within the area A (FIG. 14B), and a second configuration in which a portion of each retention member 3610, 3612 is disposed outside of the area A (FIG. 14A).

As illustrated, the proximal retention member 3610 and the distal retention member 3612 are coupled by the elastic member 3668, a portion of which is disposed within the inner area 3620 of the support member 3602. In the illustrated embodiment, the elastic member 3668 has a sidewall 3674 that defines a lumen 3676. In other embodiments, the elastic member can be, for example, a spring, an elastic band, or any other suitable device for elastically coupling the proximal retention member 3610 and the distal retention member 3612.

The proximal retention member 3610 includes a first elongate member 3630 and a second elongate member 3632, each of which are pivotally coupled to a connection member 3678 by a hinge 3660. Similarly, the distal retention member 3612 includes a first elongate member 3631 and a second elongate member 3633 each of which are pivotally coupled to a connection member 3678 by a hinge 3660.

As illustrated in FIG. 14A, when the spinal implant 3600 is in the second configuration, the elastic member 3668 exerts a biasing force on each connection member 3678, thereby causing the connection members 3678 to remain adjacent to the support member 3602. In this configuration, the first elongate member 3630 and the second elongate member 3632 are fully extended. The spinal implant 3600 is transitioned from the second configuration to the first configuration by stretching the elastic member 3668, which allows the connection members 3678 to be disposed apart from the support member 3602, thereby allowing the elongate members to move within the area A, as illustrated in FIG. 14B. The support member 3602 includes slots 3672 in which the end portion of each elongate member can be disposed to maintain the spinal implant 3600 in the first configuration.

The elastic member 3668 can be stretched by an insertion tool (not shown), a portion of which can be configured to be disposed within the lumen 3676 of the elastic member 3668. For example, a first portion of an insertion tool can engage the connection member 3678 of the proximal retention member 3610 while a second portion of the insertion tool can engage the connection member 3678 of the distal retention member 3612. The tool can then be configured to exert an outward force on each of the connection members 3678, thereby stretching the elastic member 3668 and allowing the spinal implant to transition from the second configuration to the first configuration.

While the spinal implants are shown and described above as having one or more retention members that extend substantially symmetrically from a support member when in a second configuration, in some embodiments, a spinal implant includes a retention member that extends asymmetrically from a support member when in a second configuration. For example, FIGS. 15-17 illustrate a spinal implant 3700 according to an embodiment of the invention that includes a proximal retention member 3710 and a distal retention member 3712 that extend asymmetrically from a support member 3702. As shown in FIGS. 15 and 16, the proximal retention member 3710 and the distal retention member 3712 are each repeatably positionable in a first configuration in which they are substantially disposed within the support member 3702, and a second configuration in which a portion each is disposed outside of the support member 3702.

The support member 3702 includes a sidewall 3708 that defines an inner area 3720 and two openings 3714 that connect the inner area 3720 to an area outside of the support member 3702. When the spinal implant 3700 is in the second configuration, a portion of the proximal retention member 3710 and a portion of the distal retention member 3712 extend through the openings 3714 to an area outside of the support member 3702.

In the illustrated embodiment, the proximal retention member 3710 and the distal retention member 3712 each include a first end portion 3746 and a second end portion 3744. The first end portions 3746 of the proximal retention member 3710 and the distal retention member 3712 are coupled by a connecting member 3782 that has a longitudinal axis L1 (shown in FIG. 12). In some embodiments, the connecting member 3782, the proximal retention member 3710 and the distal retention member 3712 are separate components that are coupled together to form the illustrated structure. In other embodiments, the connecting member 3782, the proximal retention member 3710 and the distal retention member 3712 are monolithically formed.

The connecting member 3782 defines a longitudinal axis L1, about which it rotates. As illustrated, as the connecting member 3782 rotates, the proximal retention member 3710 and the distal retention member 3712 also rotate, thereby causing the end portions 3744 of the proximal retention member 3710 and the distal retention member 3712 to extend outwardly through the openings 3714. In this manner, the retention member 3210 can be repeatedly transitioned between the first configuration and the second configuration.

In some embodiments, the connecting member 3782 is rotated using an insertion tool (not shown) that includes a ratchet mechanism. The insertion tool can rotate the connecting member 3782 in a number of different ways, such as, for example, manually, pneumatically or electronically.

While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. Where methods and steps described above indicate certain events occurring in certain order, those of ordinary skill in the art having the benefit of this disclosure would recognize that the ordering of certain steps may be modified and that such modifications are in accordance with the variations of the invention. Additionally, certain of the steps may be performed concurrently in a parallel process when possible, as well as performed sequentially as described above. Thus, the breadth and scope of the invention should not be limited by any of the above-described embodiments, but should be defined only in accordance with the following claims and their equivalents. While the invention has been particularly shown and described with reference to specific embodiments thereof, it will be understood that various changes in form and details may be made.

For example, although the embodiments above are primarily described as being spinal implants configured to be positioned between adjacent spinous processes, in alternative embodiments, the implants are configured to be positioned adjacent any bone, tissue or other bodily structure where it is desirable to maintain spacing while preventing axial or longitudinal movement of the implant.

Although the embodiments above have been shown and described as including a support member having a side wall defining a substantially rectangular shape, in alternative embodiments, the support member can have any number of different cross-sectional shapes, such as circular or oval. In other alternative embodiments, the support member does not include a side wall, but rather is a monolithic structure having internal cavities for containing one or more retention members. 

1. An apparatus, comprising: a support member configured to be disposed between adjacent spinous processes; a proximal retention member having a first configuration in which the proximal retention member is substantially disposed within a proximal portion of the support member and a second configuration in which a portion of the proximal retention member is disposed outside of the support member; and a distal retention member having a first configuration in which the distal retention member is substantially disposed within a distal portion of the support member and a second configuration in which a portion of the distal retention member is disposed outside of the support member.
 2. The apparatus of claim 1, wherein the support member is configured to contact the adjacent spinous processes upon spinal extension.
 3. The apparatus of claim 1, further comprising a sensor coupled to the support member, the sensor being configured to measure at least one of a pressure or a force.
 4. The apparatus of claim 1, wherein the support member is configured to be inserted between the adjacent spinous processes percutaneously.
 5. The apparatus of claim 1, wherein: the proximal retention member is configured to move from the first configuration to the second configuration and from the second configuration to the first configuration; and the distal retention member is configured to move from the first configuration to the second configuration and from the second configuration to the first configuration.
 6. The apparatus of claim 1, wherein: the proximal retention member is configured to move to its own first configuration and the distal retention member is configured to move to its own first configuration substantially simultaneously; and the proximal retention member is configured to move to its own second configuration and the distal retention member is configured to move to its own second configuration substantially simultaneously.
 7. The apparatus of claim 1, wherein: each of the proximal retention member and the distal retention member includes a first elongate member and a second elongate member configured to be slidably disposed within the first elongate member; and the support member includes a side wall defining a plurality of openings, each opening from the plurality of openings being configured to receive a portion of at least one of the first elongate member or the second elongate member from at least one of the proximal retention member or the distal retention member therethrough.
 8. The apparatus of claim 1, wherein: each of the proximal retention member and the distal retention member includes a first elongate member, a second elongate member configured to be slidably disposed within the first elongate member, and a biasing member coupled to the first elongate member and the second elongate member, the biasing member configured to retain each of the proximal retention member and the distal retention member in either one of the first configuration and the second configuration; and the support member includes a side wall defining a plurality of openings, each opening from the plurality of openings being configured to receive a portion of at least one of the first elongate member and the second elongate member from at least one of the proximal retention member or the distal retention member therethrough.
 9. The apparatus of claim 1, wherein each of the proximal retention member and the distal retention member includes: an elongate member having a longitudinal axis, a portion of the elongate member being flexible in a direction normal to the longitudinal axis of the elongate member, and a rotating member having a longitudinal axis normal to the longitudinal axis of the elongate member, the rotating member being coupled to the elongate member and configured to rotate about the longitudinal axis of the rotating member to move the elongate member along the longitudinal axis of the elongate member.
 10. The apparatus of claim 1, wherein each of the proximal retention member and the distal retention member includes: a first elongate member having a longitudinal axis, a second elongate member having a longitudinal axis coaxial with the longitudinal axis of the first elongate member, and an eccentric rotating member having an outer surface, a portion of the outer surface configured to contact a portion of each of the first elongate member and the second elongate member, the eccentric rotating member being configured to rotate such that each of the first elongate member and the second elongate member each move between their respective first configuration and the second configuration.
 11. The apparatus of claim 1, wherein: each of the proximal retention member and the distal retention member includes a first elongate member configured to extend through a first opening defined in the support member, a second elongate member configured to extend through a second opening defined in the support member, and a hinge having a longitudinal axis, the hinge configured to pivotally couple the first elongate member and the second elongate member along the longitudinal axis and to move in a direction normal to the longitudinal axis such that each of the first elongate member and the second elongate member moves between the first configuration and the second configuration.
 12. The apparatus of claim 1, wherein: the proximal retention member is configured to be positioned in a third configuration in which the proximal retention member is substantially disposed within the proximal portion of the support member, the third configuration being different than the first configuration; and the distal retention member is configured to be positioned in a third configuration in which the distal retention member is substantially disposed within the distal portion of the support member, the third configuration being different than the first configuration.
 13. An apparatus, comprising: a support member including a side wall having an outer surface, at least a portion of the outer surface being configured to be disposed between adjacent spinous processes, the outer surface defining an area normal to a longitudinal axis of the support member; a proximal retention member having a first configuration in which the proximal retention member is disposed within the area and a second configuration in which a portion of the proximal retention member is disposed outside of the area; and a distal retention member having a first configuration in which the distal retention member is disposed within the area and a second configuration in which a portion of the distal retention member is disposed outside of the area.
 14. The apparatus of claim 13, wherein a portion of each of the proximal retention member and the distal retention member is configured to be disposed outside of the support member.
 15. The apparatus of claim 13, further comprising an elastic member coupled to the proximal retention member and the distal retention member, the elastic member configured to retain each of the proximal retention member and the distal retention member in either one of the first configuration and the second configuration.
 16. The apparatus of claim 13, wherein the support member is configured to be inserted between the adjacent spinous processes percutaneously.
 17. An apparatus, comprising: a support member configured to be percutaneously inserted into a body and disposed between adjacent spinous processes, the support member having a longitudinal axis and a side wall, the side wall being substantially parallel to the longitudinal axis and defining an inner area and an opening that connects the inner area and an area outside the support member; and a retention member having a first configuration in which the retention member is substantially disposed within the inner area and a second configuration in which a portion of the retention member is disposed through the opening to the area outside the support member.
 18. A method, comprising: percutaneously inserting into a body a support member configured to be disposed between adjacent spinous processes, the support member having a longitudinal axis and a side wall, the side wall being substantially parallel to the longitudinal axis and defining an inner area and an opening that connects the inner area and an area outside the support member, the support member including a retention member having a first configuration in which the retention member is substantially disposed within the inner area, and a second configuration in which a portion of the retention member is disposed through the opening to the area outside the support member; disposing the support member to a location between the adjacent spinous processes when retention member is in the first configuration; and moving the retention member from the first configuration to the second configuration.
 19. The method of claim 18, wherein the location is a first location, the method further comprising: moving the retention member from the second configuration to the first configuration; and disposing the support member in a second location, the second location being different from the first location.
 20. The method of claim 18, wherein the location is a first location, the method further comprising: moving the retention member from the second configuration to the first configuration; disposing the support member in a second location, the second location being between the adjacent spinous processes and different from the first location; and moving the retention member from the first configuration to the second configuration after the support member has been disposed in the second location.
 21. The method of claim 18, further comprising: moving the retention member from the second configuration to the first configuration; and disposing the support member in a second location, the second location being outside of the body.
 22. An apparatus, comprising: a support member configured to be disposed between adjacent spinous processes, the support member having a longitudinal axis; and a retention member coupled to the support member, the retention member having a longitudinal axis that is normal to the longitudinal axis of the support member, the retention member being configured to move along its longitudinal axis from a first configuration to a second configuration.
 23. The apparatus of claim 22, wherein: the retention member is configured to allow movement of the support member along the longitudinal axis of the support member when in the first configuration; and the retention member is configured to limit movement of the support member along the longitudinal axis of the support member when in the second configuration.
 24. The apparatus of claim 22, wherein the retention member is configured to contact the adjacent spinous processes when in the second configuration.
 25. The apparatus of claim 22, wherein: the support member includes a side wall that defines an inner area and an opening that connects the inner area and an area outside the support member; the retention member is substantially disposed within the inner area when in the first configuration; and a portion of the retention member is disposed through the opening to the area outside the support member when in the second configuration. 